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Enhanced expression of vsmNOS mRNA in glomeruli from rats with unilateral ureteral obstruction
K Moridaira1, H Yanagisawa, M Nodera
1Department of Hygiene and Preventive Medicine, Faculty of Medicine, Saitama Medical School, Saitama, Japan.
Background:
The vasodilatory/cytotoxic gas, nitric oxide (NO), is associated with an alteration in glomerular hemodynamics seen after the induction of ureteral ligation. As yet the type of nitric oxide synthase (NOS) protein involved in the mechanism has not been clearly established in the unilateral ureteral obstruction (UUO) model.
Methods:
Using reverse transcription (RT)-polymerase chain reaction (PCR), the expression and localization of vascular smooth muscle-derived nitric oxide synthase (vsmNOS) mRNA were examined in glomeruli from sham-operated control (SOC) rats and rats with UUO of three hours duration. Moreover, the effect of endogenous angiotensin II on the expression of vsmNOS mRNA in glomeruli was explored using SOC rats and rats with UUO that were pretreated or not with enalapril, an angiotensin-converting enzyme inhibitor.
Results:
The expression of vsmNOS mRNA was significantly greater in glomeruli of rats with UUO than in those of SOC rats. In rats with UUO, the expression of vsmNOS mRNA was substantially increased in glomeruli of the obstructed kidney (OK) compared to the contralateral, nonobstructed kidney (CLK). Suppression of angiotensin II production in vivo with enalapril restored the expression of vsmNOS mRNA in glomeruli of the CLK and OK from rats with UUO to levels comparable to that seen in glomeruli from SOC rats. In addition, the in situ RT-PCR analysis, a novel method for mRNA identification in cells and tissue, revealed that vsmNOS mRNA was expressed in the cytoplasm of glomerular mesangial and epithelial cells in SOC rats and rats with UUO.
Conclusions:
An increase in vsmNOS mRNA expression in glomeruli of the CLK and OK from rats with UUO may be mediated by increased action of endogenous angiotensin II that occurs after the onset of ureteral obstruction. Enhanced expression of vsmNOS mRNA in glomeruli of the OK compared to the CLK may be due to differences in levels of angiotensin II acting on the two kidneys in vivo. Additionally, the expression of vsmNOS mRNA in glomeruli originates in mesangial and epithelial cells in SOC rats and rats with UUO.